Copper-base alloys



United States Patent 3,049,424 COPPER-BASE ALLOYS Ronald James Malcolm Payne, London, and Alfred William Owen Webb, Bromley, England, assignors to J. Stone & Company (Charlton) Limited, London, England No Drawing. Filed Oct. 14, 1958, Ser. No. 767,098 Claims priority, application Great Britain Oct. 15, 1957 Claims. (Cl. 75-161) This invention concerns improvements relating to copper-base alloys containing manganese and aluminum and seeks to provide an alloy which is intended to be used primarily, but not exclusively, in the wrought form and which can possess good cold-working qualities, useful mechanical properties, good welding qualities, good properties at elevated temperatures and good resistance to corrosion.

Simple ternary copper-mauganese-aluminum alloys have been known for a long time and the use of singlephase alloys of this type has been proposed for electrical purposes. It is, however, notable that little or no practical use has been made of them for ordinary engineering purposes. A feature of these alloys which accounts, at least in part, for this neglest is their tendency to corrosion by de-aluminification in acid and salt solutions. The addition of nickel brings about an improvement in corrosion resistance which may be sufiicient for parts exposed to mild corrosive conditions only. The effects of nickel are, however, limited and nickel-bearing alloys still dealuminify sufiiciently rapidly in strong acids to prevent their use under these conditions.

It hzis now been discovered that the elements arsenic and antimony, of group V of the periodic table, have, when added in minute amounts, a profound influence on the corrosion of copper-manganese-alurninum alloys containing nickel, inhibiting the tendency to de-aluminification in acid and salt solutions.

In accordance with the invention, therefore, a singlephase copper-base alloy comprises manganese 5 to about 13%, aluminum 1 /2 to about 5%, nickel not more than 6% iron not more than 5%, and arsenic and/ or antimony 0.0 1 to 0.2%, the remainder being copper. Generally the manganese and aluminum contents will be within the limits of 5 to 13% and 2. to 5% respectively, the mangancse content exceeding the aluminum content.

Although the inhibitor elements, arsenic and antimony, restrain de-aluminification when added alone, they show a very much better elfect when nickel is present. Generally not more than 3% of nickel will be used. The inhibitor elements are also eifective in the presence of iron in amounts up to 5%, though in general the alloys do not contain more than 3 /2 of the latter element. Iron refines the grain and improves the mechanical properties of copper-manganese-aluminum and copper-manganese-aluminum-nickel alloys. It may be added to or omitted from the alloys, depending on whether a strong or soft product is required and upon the purpose of use of the alloy. For instance, where high mechanical properties are required, an iron addition would generally be desirable. Where, on the other hand, the ability of the material to withstand severe working operations is more important than the mechanical properties in the condition as supplied (this is the case with many semifinished products requiring to be bent, flanged or riveted) then it might be preferable to omit iron. The following table gives the properties of representative alloys with and without iron and in their softest possible (fully annealed) condition and illustrates the marked influence of iron.

3,049,424 Patented Aug. 14, 1962 Table I 0.1% Ultimate Elonga- Viekers Proof Tensile tion Pyramid Iron Percent Stress, Strength, Percent Hardness Tons/sq. Tons/sq. No.

in. in.

Tin is admissible in amounts up to 3%.

In addition to arsenic or antimony, a lesser amount of phosphorus may also be present and may assist in inhibiting de-alurninification.

Elements to be avoided in preparing alloys in accordance with the invention are those which are generally objectionable in copper-base alloys, for example bismuth.

A typical copper base alloy to which arsenic and/or antimony may be added with advantage in an amount of 0.05% may accordingly comprise 12% of manganese, 4% of aluminum, 2% of nickel and 2% of iron. 'In another typical alloy, the manganese may amount to 8%.

For illustrative comparison, two alloys containing 12% of manganese, 4% of aluminum, 2% of nickel and 3% of iron were prepared, one without further addition and the other with an addition of 0.05% of antimony. For the purposes of the test, the alloys were taken in thecast form and disc-shaped specimens were prepared by machining. These specimens were immersed in a 50% sulphuric acid solution maintained at 60 C. The solution was kept in motion in relation to the specimens and was also aerated by bubbling air through it. After 20 days, the specimens were removed, sectioned and polished for microscopic examination. The alloy without antimony showed evidence of de-aluminification in the form of a layer of copper 0.1 mm. deep, whereas the alloy containing antimony showed no copper. Similar inhibitive effects were observed with an addition of arsenic.

Tests on the material in the wrought condition also, in which it is more generally used, have confirmed the usefulness of arsenic and antimony in preventing de-aluminification in wrought alloys. In general, arsenic and antimony contents of 0.01 to 0.08% have given good results.

Advantageous properties which can be obtained with alloys in accordance with the invention are:

(a) Good working qualities, particularly in the cold.

(b) A wide range of mechanical properties varying from those of soft, highly ductile, compositions to alloys o f high proof stress and strength.

Properties of a soft and highly ductile alloy have already been given in the cases of the iron-free composition in Table I. Properties of alloys containing 2% or more of iron and falling within the composition range of this specification in respect to manganese, aluminum, nickel, arsenic and antimony are as follows:

(c) Good corrosion resistance, in particular a high resistance to de-aluminification in acids and other solutions.

(d) Good welding qualities associated with the presence of manganese, which provides a complex oxide film having desirable qualities and prevents brittleness by inhibiting the breakdown of any beta phase which may be formed. In particular, alloys having welding qualities better than those of standard single-phase aluminum bronzes can be produced.

The strengths of welds in these alloys lie in the range 33 to 36 tons per square inch and are thus considerably higher than those obtained with the said bronzes.

(e) Good high-temperature properties, including a high recrystallisation temperature (750 C.) and a good retention of strength and a good resistance to creep at elevated temperatures.

(f) Good properties are obtainable at sub-zero temperatures, both strength and ductility increasing progressively as the temperature is lowered, as illustrated by the following values:

In addition, the impact strength increases by 25-30%,

as the temperature is reduced from 0 to l89 degrees C.

We claim:

1. A single-phase copper-base alloy comprising from about 5% to about 13% manganese, 2% to about 5% aluminum, not more than 6% nickel, and 0.01 to 0.2% of at least one of the elements selected from the group consisting of arsenic and antimony.

2. A single-phase copper base alloy comprising about 5 to 13% manganese, about 1 /2 to 5% aluminum, not more than 6% nickel, not more than 5% of iron, not more than 3% of tin, not more than 0.0025 of bismuth, and 0.01 to 0.2% of at least one of the elements selected from the group consisting of arsenic and antimony.

3. An alloy as claimed in claim 2 and comprising also a content of phosphorus less than the combined content of the said elements arsenic and antimony.

4. An alloy as claimed in claim 2, wherein the content of arsenic and antimony is between 0.01 and 0.08%.

5. A single-phase copper-base alloy comprising 12% of manganese, 4% of aluminum, 2% of nickel, 2% of iron, not more than 3% of tin, and 0.05% of at least one of the elements selected from the group consisting of arsenic and antimony.

References Cited in the file of this patent UNITED STATES PATENTS Morris Sept. 14, 1937 Payne et a1. Aug. 16, 1955 OTHER REFERENCES 

1. A SINGLE-PHASE COPPER-BASE ALLOY COMPRISING FROM ABOUT 5% TO ABOUT 13% MANGANESE, 2% TO ABOUT 5% ALUMINUM, NOT MORE THAN 6% NICKEL, AND 0.01 TO 0.2% OF AT LEAST ONE OF THE ELEMENTS SELECTED FROM THE GROUP CONSISTING OF ARSENIC AND ANTIMONY. 